The most probable cause for the soft keys and numeric keypad not working is that you have a standard RS232 cable plugged into the I/O port of the Mx200.  

The I/O port is a 9 pin male D connector on the back of the Mx200 readout.  It is wired to support a remote-wired keypad, footswitch, and RS232 communications.  Because it is wired for a remote keypad and footswitch, plugging in a standard RS232 cable will prevent the soft keys and numeric keypad on the front of the Mx200 from working.  It can also cause other damage to the Mx200.

If you wish to use RS232 communication with the Mx200 readout, please read the "Why doesn't a standard RS232 serial cable or an RS232 to USB cable work on the Mx200?" article.

If this is not the issue and you do not have an RS232 cable plugged into the Mx200, please open a Support Ticket.